Saliva is the principal protective agent for the mouth and thus is of primary importance to oral health maintenance. Perturbations of salivary secretion mechanisms can consequently lead to serious oral health problems. The objective of this project is to study the membrane and cellular processes which underlie the phenomenon of salivary fluid secretion and thus to contribute to our understanding of the fluid secretory process in normal and diseased states. Because similar secretory mechanisms are thought to be common to a number of other exocrine glands, this information should be of rather broad applicability and interest. During the present reporting period our specific areas of focus were the following. (1) Studies of the regulation of the rat parotid acinar Na-K-2Cl cotransporter by muscarinic stimulation were continued. (2) The properties of the anion binding sites on the parotid Na-K-2Cl cotransporter were characterized. (3) Cloning and sequencing of the rat parotid Na-K-2Cl cotransporter was continued and functional expression studies were begun. (4) The effects of IP3 on calcium release from intracellular stores were studied in permeabilized HSY cells.